# US 11,298,882 B2 · Carriage synchronization of a multi-carriage three-dimensional printer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,298,882 B2 - Document ID: US11298882B2 - Status: Granted - Kind: B2 - Application number: 16/075,498 - Filed: 2017-04-21 - Published: 2021-07-08 - Granted: 2022-04-12 - Earliest claimed: 2017-04-21 - Assignees: Hewlett-Packard Development Company, L.P. - Applicants: Hewlett-Packard Development Company, L.P. - Inventors: Michael Ewe; Eric Collins; Donnell D. Daniels - Web page: https://patentgrep.com/patent/US11298882B2 ## CPC - B29C 64/393: for controlling or regulating additive manufacturing processes - B29C 64/205: Means for applying layers - B29C 64/227: Driving means - B29C 64/236: for motion in a direction within the plane of a layer - B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor - B33Y 50/02: for controlling or regulating additive manufacturing processes - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING ## Abstract An example three-dimensional printing system includes a first carriage, a second carriage, and a synchronization controller. The synchronization controller is coupled to the first carriage and the second carriage to synchronize movements of the first carriage and the second carriage. The synchronization controller is to avoid interference between the first carriage and the second carriage. ## Claims ### Claim 1 A three-dimensional printing system, comprising: a first carriage moveable along a first linear path; a second carriage moveable along a second, different linear path, the first and second carriages structured to distribute build material for the printing system; a number of encoders to output an indication of a position of each of the first and second carriages along the first and second linear paths respectively, wherein the first and second linear paths intersect; and a synchronization controller to receive output of the number of encoders to synchronize movements of the first carriage and the second carriage and to avoid interference between the first carriage and the second carriage where the first and second linear paths intersect; wherein to avoid interference between the first carriage and the second carriage, the synchronization controller stops the second carriage if the second carriage passes a trigger position while the first carriage is in a collision zone. ### Claim 2 (depends on 1) The three-dimensional printing system of claim 1, wherein the first carriage is to deliver a build material to a staging zone; and the second carriage is to spread the build material over a build zone and to fuse the build material, wherein the first carriage moves in a direction perpendicular to the second carriage, the second carriage structured to move through the staging zone and the build zone. ### Claim 3 (depends on 2) The three-dimensional printing system of claim 2, further comprising: a third carriage to apply agents to the build material over the build zone, wherein the synchronization controller is further in control of movement of the third carriage and is to synchronize movements of the first, second and third carriages and to avoid interference between different ones of the carriages. ### Claim 4 (depends on 3) The three-dimensional printing system of claim 3, wherein the synchronization controller is further to move the second and third carriages together over the build zone while preventing collision between the second and third carriages moving together. ### Claim 5 (depends on 4) The three-dimensional printing system of claim 4, wherein the synchronization controller is further to move the second and third carriages together over the build zone in a first direction to complete a printing traverse of the build zone and then in a second, opposite direction to complete a fusing traverse of the build zone, the second and third carriages moving next to each other during the printing and fusing traverses. ### Claim 6 (depends on 1) The three-dimensional printing system of claim 1, wherein to synchronize the movements of the first carriage and the second carriage, the synchronization controller determines that a time for the second carriage to exit a collision zone is less than a time for the first carriage to enter the collision zone. ### Claim 7 (depends on 1) The three-dimensional printing system of claim 1, wherein to synchronize the movements of the first carriage and the second carriage, the synchronization controller calculates and maintains a separation between the first carriage and the second carriage based on current position measurements from the number of encoders. ### Claim 8 (depends on 7) The three-dimensional printing system of claim 7, wherein to avoid interference between the first carriage and the second carriage, the synchronization controller predicts future locations of the first carriage and second carriage based on plurality of position measurements from the number of encoders. ### Claim 9 A method, comprising: moving a first carriage across a staging zone to form a ribbon of build material across the staging zone; moving a second carriage through the staging zone and into a build zone to distribute the ribbon of build material as a layer of build material in the build zone, the second carriage moving in a direction perpendicular to the movement of the first carriage, a collision zone existing at an intersection of a path of the first carriage and a path of the second carriage; determining that the first carriage is in the collision zone; determining if a first time for the first carriage to exit the collision zone is less than a second time for a second carriage to enter the collision zone; and if the first time is less than the second time, starting movement of the second carriage; else if the first time is not less than the second time, delaying movement of the second carriage to avoid a collision between the first and second carriages in the collision zone; and to further avoid interference between the first carriage and the second carriage, stopping the second carriage if the second carriage passes a trigger position while the first carriage is in the collision zone. ### Claim 10 (depends on 9) The method of claim 9, further comprising: determining if a distance between the first carriage and the second carriage is less than a threshold distance to safely stop the carriages; and if the distance between the first carriage and the second carriage is less than the threshold distance, start moving the third carriage to a safe position. ### Claim 11 (depends on 9) The method of claim 9, further comprising retracting a spreading device of the second carriage to avoid disturbing a ribbon of build material in the staging zone when the second carriage returns across the staging zone to a starting position. ### Claim 12 (depends on 9) The method of claim 9, further comprising halting the first carriage when the second carriage fails to move as commanded by a synchronization controller. ### Claim 13 (depends on 9) The method of claim 9, with a synchronization controller, timing movement of the first carriage to enter the staging zone just as the second carriage leaves the collision zone. ### Claim 14 A non-transitory computer-readable storage medium encoded with instructions executable by a processor of a computing system, the computer-readable storage medium comprising instructions to: synchronize movements of a first carriage and a second carriage that are distributing build material in a three-dimensional printing system, wherein the first and second carriages move along different, intersecting linear paths; avoid interference between the first carriage and the second carriage based on encoder data indicating a current location of the first and second carriages to prevent a collision between the first and second carriages; synchronize movements of the second carriage and a third carriage; and avoid interference between the second carriage and the third carriage based on encoder data indicating a current location of the second and third carriages to prevent a collision between the second and third carriages; and stopping the second carriage if the second carriage passes a trigger position while the first carriage is in a collision zone. ### Claim 15 (depends on 14) The non-transitory computer-readable storage medium of claim 14, wherein to synchronize the movements of the first and second carriages, the non-transitory machine-readable storage medium further includes instructions to: determine that the first carriage is in a collision zone; determine if a first time for the first carriage to exit the collision zone is less than a second time for the second carriage to enter the collision zone; and if the first time is less than the second time, start movement of the second carriage; else, if the first time is not less than the second time, delay movement of the second carriage. ### Claim 16 (depends on 14) The non-transitory computer-readable storage medium of claim 14, wherein to synchronize the movements of the second and third carriages, the non-transitory machine-readable storage medium further includes instructions to: determine if a distance between the second carriage and a third carriage is less than a threshold distance to safely stop the carriages; and if the distance between the second carriage and a third carriage is less than the threshold distance, move the third carriage toward a safe position; else continue to monitor the distance between the second and third carriages. ### Claim 17 (depends on 16) The non-transitory computer-readable storage medium of claim 16, wherein to avoid interference between the first carriage and the second carriage, the non-transitory machine-readable storage medium further includes instructions to: determine if the third carriage is moving toward the safe position; and if the third carriage is not moving toward the safe position, stop the second and third carriages; else continue to move the third carriage toward the safe position.